1. Technical Field
The present invention relates to a semiconductor device, and in particular to a semiconductor device having pads, such as bonding pads, provided over a substrate.
2. Related Art
In recent years, low-dielectric-constant insulating film (low-k film), typically having a dielectric constant (k-value) of 2.7 or smaller, has increasingly been used for insulating interlayers in multi-layered interconnect structures. However, the low-k film is generally poor in mechanical strength. There has therefore been a problem in that the insulating interlayer may cause crack or separation when the bonding pads are applied with load in the process of wire bonding, probing and so forth, and thereby yield of the final products tends to degrade.
International Patent publication No. WO2005/096364 describes a semiconductor device which uses the low-dielectric-constant insulating interlayer having poor strength and adhesiveness, configured so that a large number of reinforcing via patterns, not electrically connected to a circuit, are formed in a region where reinforcing interconnect patterns formed in the upper and lower interconnect layers overlap with each other, so as to connect the reinforcing interconnect patterns with each other. According to the description, the separation or rupture of films in the manufacturing process or packaging may be suppressible, by virtue of increased structural strength.
Japanese Laid-Open Patent Publication No. 2004-235416 describes a semiconductor device having bonding pads formed on a semiconductor substrate; an upper copper interconnect layer formed below the bonding pads, and having a ratio of area of copper larger than that of a layer in which circuit interconnects are formed; and a lower copper interconnect layer electrically isolated from the upper copper interconnect layer, and formed more closer to the semiconductor substrate than the upper copper interconnect layer is.